Greenhouse gas emission analysis for USA fluid milk processing plants: Processing,packaging, and distribution

A gate-to-gate life cycle assessment was conducted to evaluate the Global Warming Potential associated with USA fluid milk processing. Data collected from 50 fluid milk processing plants were used to construct a life cycle assessment model for the greenhouse gas (GHG) emissions across the milk processing system, from raw milk entering the plant’s refrigerated storage silo through delivery of packaged fluid milk to retail store’s loading dock. Carbon dioxide equivalent (CO₂e) emissions associated with the processing, packaging, and distribution in the processing of packaged fluid milk were investigated. Upstream emissions associated with raw materials, extraction, and transportation were included. Average GHG emissions for processing, packaging and distribution were 0.077, 0.054 and 0.072 kg CO₂e kg⁻¹ packaged fluid milk, respectively. Overall GHG emissions were 0.203 (±0.017) kg CO₂e kg⁻¹ packaged fluid milk with major individual GHG contributors being plant electricity usage (27% of total) and truck fleet tailpipe emissions (29% of total).     

Greenhouse gas emissions from milk production and consumption in the United States: A cradle-to-grave life cycle assessment circa 2008

This article presents a cradle-to-grave analysis of the United States fluid milk supply chain greenhouse gas (GHG) emissions that are accounted from fertilizer production through consumption and disposal of milk packaging. Crop production and on-farm GHG emissions were evaluated using public data and 536 farm operation surveys. Milk processing data were collected from 50 dairy plants nationwide. Retail and consumer GHG emissions were estimated from primary data, design estimates, and publicly available data. Total GHG emissions, based primarily on 2007 to 2008 data, were 2.05 (90% confidence limits: 1.77–2.4) kg CO₂e per kg milk consumed, which accounted for loss of 12% at retail and an additional 20% loss at consumption. A complementary analysis showed the entire dairy sector contributes approximately 1.9% of US GHG emissions. While the largest GHG contributors are feed production, enteric methane, and manure management; there are opportunities to reduce impacts throughout the supply chain.     

Feeding strategies and manure management for cost-effective mitigation of greenhouse gas emissions from dairy farms in Wisconsin

Greenhouse gas (GHG) emissions from dairy farms are a major concern. Our objectives were to assess the effect of mitigation strategies on GHG emissions and net return to management on 3 distinct farm production systems of Wisconsin. A survey was conducted on 27 conventional farms, 30 grazing farms, and 69 organic farms. The data collected were used to characterize 3 feeding systems scaled to the average farm (85 cows and 127 ha). The Integrated Farm System Model was used to simulate the economic and environmental impacts of altering feeding and manure management in those 3 farms. Results showed that incorporation of grazing practices for lactating cows in the conventional farm led to a 27.6% decrease in total GHG emissions [−0.16 kg of CO₂ equivalents (CO₂eq)/kg of energy corrected milk (ECM)] and a 29.3% increase in net return to management (+$7,005/yr) when milk production was assumed constant. For the grazing and organic farms, decreasing the forage-to-concentrate ratio in the diet decreased GHG emissions when milk production was increased by 5 or 10%. The 5% increase in milk production was not sufficient to maintain the net return; however, the 10% increase in milk production increased net return in the organic farm but not on the grazing farm. A 13.7% decrease in GHG emissions (−0.08 kg of CO₂eq/kg of ECM) was observed on the conventional farm when incorporating manure the day of application and adding a 12-mo covered storage unit. However, those same changes led to a 6.1% (+0.04 kg of CO₂eq/kg of ECM) and a 6.9% (+0.06 kg of CO₂eq/kg of ECM) increase in GHG emissions in the grazing and the organic farms, respectively. For the 3 farms, manure management changes led to a decrease in net return to management. Simulation results suggested that the same feeding and manure management mitigation strategies led to different outcomes depending on the farm system, and furthermore, effective mitigation strategies were used to reduce GHG emissions while maintaining profitability within each farm.     

Base-line susceptibility of field populations of Rhyzopertha dominica (F.) to spinosad in Australia

Spinosad has recently been registered in several countries for long-term protection against a range of stored grain insects including the lesser grain borer, Rhyzopertha dominica (F.). The potential for development of resistance to spinosad is demonstrated by the existence of resistance in many insect pests of agriculture. The aim of this study was to determine the base-line susceptibility of R. dominica to spinosad, to provide a basis for future resistance monitoring. Eighteen insect populations of R. dominica were collected from field storage sites across four States within Australia, and exposed to a range of spinosad rates, including its current registered rate of 1 mg kg⁻¹ (1 ppm). Base-line susceptibility was assessed based on adult mortality and production of F₁ adults. Comparison of LC₅₀ and LC_99.9 indicated the existence of low level of variation among the tested R. dominica populations, in their susceptibility to spinosad. For adults, there was a narrow range of LC₅₀ values with the highest (0.027 ppm) being 2.5 × the lowest (0.011 mg kg⁻¹). Similarly, LC_99.9 values showed a narrow range with the highest (0.36 mg kg⁻¹) being 3.6 × the lowest (0.10 mg kg⁻¹). For adult progeny produced in spinosad treated grain, there was a narrow range of LC₅₀ values with the highest (0.025 mg kg⁻¹) being 5 × the lowest (0.004 mg kg⁻¹) and the highest LC_99.9 values (0.67 mg kg⁻¹) being 5 × the lowest LC_99.9 (0.13 mg kg⁻¹). Based on the data generated from this study, we recommend a dose of 1 mg kg⁻¹(1 ppm) to be used to discriminate between susceptible and resistant populations for future resistance monitoring programs.     

The effect of feed demand on greenhouse gas emissions and farm profitability for organic and conventional dairy farms

The reduction of product-related greenhouse gas (GHG) emissions in milk production appears to be necessary. The reduction of emissions on an individual farm might be highly accepted by farm owners if it were accompanied by an increase in profitability. Using life cycle assessments to determine the product carbon footprints (PCF) and farm-level evaluations to record profitability, we explored opportunities for optimization based on analysis of 81 organic and conventional pasture-based dairy farms in southern Germany. The objective of the present study was to detect common determining factors for low PCF and high management incomes (MI) to achieve GHG reductions at the lowest possible operational cost. In our sample, organic farms, which performed economically better than conventional farms, produced PCF that were significantly higher than those produced by conventional farms [1.61 ± 0.29 vs. 1.45 ± 0.28 kg of CO₂ equivalents (CO₂eq) per kg of milk; means ± SD)]. A multiple linear regression analysis of the sample demonstrated that low feed demand per kilogram of milk, high grassland yield, and low forage area requirements per cow are the main factors that decrease PCF. These factors are also useful for improving a farm's profitability in principle. For organic farms, a reduction of feed demand of 100 g/kg of milk resulted in a PCF reduction of 105 g of CO₂eq/kg of milk and an increase in MI of approximately 2.1 euro cents (c)/kg of milk. For conventional farms, a decrease of feed demand of 100 g/kg of milk corresponded to a reduction in PCF of 117 g of CO₂eq/kg of milk and an increase in MI of approximately 3.1 c/kg of milk. Accordingly, farmers could achieve higher profits while reducing GHG emissions. Improved education and training of farmers and consultants regarding GHG mitigation and farm profitability appear to be the best methods of improving efficiency under traditional and organic farming practices.     

Immunomodulatory activities of Lactobacillus rhamnosus ZDY114 and donkey milk in BALB/c mice

The immunomodulatory activity of Lactobacillus rhamnosus ZDY114 and donkey milk in BALB/c mice was evaluated by assessing the splenic lymphocyte transformation, haemolytic complement activity, carbon clearance ability and natural killer cell activity. Results showed donkey milk (5 g kg⁻¹) in combination with L. rhamnosus ZDY114 (5 × 10⁷ cfu mL⁻¹) exhibited a significant increase in splenic lymphocyte proliferation, carbon granule engulfing ability and natural killer cell activity when compared with donkey milk or L. rhamnosus ZDY114 alone (p < 0.05). An elevated response in serum haemolytic activity was only observed when compared with L. rhamnosus ZDY114. In conclusion, donkey milk (5 g kg⁻¹) in combination with L. rhamnosus ZDY114 (5 × 10⁷ cfu mL⁻¹) was able to enhance specific immune functions.     

Selenium supplementation of diets of dairy cows to produce Se-enriched cheese

Selenium (Se) deficiency in people and animals is a nutritional problem in many regions of the world. Ten mid-lactation Estonian Red dairy cows were supplemented for 64 days with inorganic Se [0.39 mg kg⁻¹ in total mixed ration (TMR)] followed by a 57-day period of supplementation with organic and inorganic Se (0.44 mg kg⁻¹ in TMR), according to EU directives on maximum allowed amounts. Feeding organic Se increased Se content in blood (from 186.5 to 287.9 μg kg⁻¹), milk (from 17.1 to 51.8 μg kg⁻¹) and Edam-type cheese made there from (from 146 to 361 μg kg⁻¹). Se content in milk after supplementation was high enough to produce a cheese enabling the nutrition claim “high in Se” and related health claims. The concentration of the main primary oxidation products of linoleic acid (oxylipins) was low and leukotoxin diols were found in trace amounts; the oxidative stability of cheeses was high.     

Antihypertensive activity of milk fermented by Enterococcus faecalis strains isolated from raw milk

A total of 231 microorganisms were isolated from raw cow milk samples and the angiotensin-converting enzyme-inhibitory (ACEI) activity of the resultant fermented milk produced with the isolated microorganisms was assayed. Forty-six of these microorganisms were selected on the basis of high ACEI activity. Four Enterococcus faecalis strains stood out as producers of fermented milk with potent ACEI activity (IC₅₀ (the protein concentration that inhibits 50% of ACE activity): 34–59 μg mL⁻¹). Single doses (5 mL kg⁻¹) of the whey fraction obtained from these fermented milk samples were administered to spontaneously hypertensive rats (SHR) and to normotensive Wistar-Kyoto (WKY) rats in order to investigate their possible antihypertensive activity. Highly significant decreases in the systolic blood pressure (SBP) and in the diastolic blood pressure (DBP) were observed when the fermented milk was administered to SHR. Nevertheless, the fermented milk did not modify the SBP and the DBP of the WKY rats. Raw cow milk is an excellent source of wild lactic acid bacteria able to produce fermented milk with antihypertensive activity and antihypertensive activity of milk fermented by Enterococcus faecalis strains was associated with peptides different from Ile-Pro-Pro and Val-Pro-Pro.     

Carbon footprint of Canadian dairy products: Calculations and issues

The Canadian dairy sector is a major industry with about 1 million cows. This industry emits about 20% of the total greenhouse gas (GHG) emissions from the main livestock sectors (beef, dairy, swine, and poultry). In 2006, the Canadian dairy herd produced about 7.7 Mt of raw milk, resulting in about 4.4 Mt of dairy products (notably 64% fluid milk and 12% cheese). An integrated cradle-to-gate model (field to processing plant) has been developed to estimate the carbon footprint (CF) of 11 Canadian dairy products. The on-farm part of the model is the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES). It considers all GHG emissions associated with livestock production but, for this study, it was run for the dairy sector specifically. Off-farm GHG emissions were estimated using the Canadian Food Carbon Footprint calculator, (cafoo)²-milk. It considers GHG emissions from the farm gate to the exit gate of the processing plants. The CF of the raw milk has been found lower in western provinces [0.93 kg of CO₂ equivalents (CO₂e)/L of milk] than in eastern provinces (1.12 kg of CO₂e/L of milk) because of differences in climate conditions and dairy herd management. Most of the CF estimates of dairy products ranged between 1 and 3 kg of CO₂e/kg of product. Three products were, however, significantly higher: cheese (5.3 kg of CO₂e/kg), butter (7.3 kg of CO₂e/kg), and milk powder (10.1 kg of CO₂e/kg). The CF results depend on the milk volume needed, the co-product allocation process (based on milk solids content), and the amount of energy used to manufacture each product. The GHG emissions per kilogram of protein ranged from 13 to 40 kg of CO₂e. Two products had higher values: cream and sour cream, at 83 and 78 kg of CO₂e/kg, respectively. Finally, the highest CF value was for butter, at about 730 kg of CO₂e/kg. This extremely high value is due to the fact that the intensity indicator per kilogram of product is high and that butter is almost exclusively fat. Protein content is often used to compare the CF of products; however, this study demonstrates that the use of a common food component is not suitable as a comparison unit in some cases. Functionality has to be considered too, but it might be insufficient for food product labeling because different reporting units (adapted to a specific food product) will be used, and the resulting confusion could lead consumers to lose confidence in such labeling. Therefore, simple units might not be ideal and a more comprehensive approach will likely have to be developed.     

Extrusion improved the physical and chemical properties of dietary fibre from bamboo shoot by-products

Bamboo shoot by-products are regarded as waste and environmental pollutant. This study aimed to improve the functional properties of dietary fibre from bamboo shoot by-products. After CO₂ extrusion, the particle size of CO₂-extruded bamboo fibre was 17.6% lower than that of the control, and its specific surface area was 2.85 times that of the control. The soluble dietary fibre content was significantly increased from 5.64 g/100 g to 11.05 g/100 g (P < 0.05), and the capacities for water holding, swelling and oil holding were remarkably improved. The cholesterol adsorption of CO₂-extruded bamboo fibre was increased from 96.54 μg g⁻¹ to 174.65 μg g⁻¹ (pH 7.0), and its nitrite ion adsorption capacity was increased from 503.33 μg g⁻¹ to 657.27 μg g⁻¹ (pH 2.0). In summary, the structural changes of bamboo fibre such as internal porosity, surface roughening and low crystallinity indicated that its functional properties were improved after CO₂ extrusion.     

A case study of the carbon footprint of milk from high-performing confinement and grass-based dairy farms

Life-cycle assessment (LCA) is the preferred methodology to assess carbon footprint per unit of milk. The objective of this case study was to apply an LCA method to compare carbon footprints of high-performance confinement and grass-based dairy farms. Physical performance data from research herds were used to quantify carbon footprints of a high-performance Irish grass-based dairy system and a top-performing United Kingdom (UK) confinement dairy system. For the US confinement dairy system, data from the top 5% of herds of a national database were used. Life-cycle assessment was applied using the same dairy farm greenhouse gas (GHG) model for all dairy systems. The model estimated all on- and off-farm GHG sources associated with dairy production until milk is sold from the farm in kilograms of carbon dioxide equivalents (CO₂-eq) and allocated emissions between milk and meat. The carbon footprint of milk was calculated by expressing GHG emissions attributed to milk per tonne of energy-corrected milk (ECM). The comparison showed that when GHG emissions were only attributed to milk, the carbon footprint of milk from the Irish grass-based system (837 kg of CO₂-eq/t of ECM) was 5% lower than the UK confinement system (884 kg of CO₂-eq/t of ECM) and 7% lower than the US confinement system (898 kg of CO₂-eq/t of ECM). However, without grassland carbon sequestration, the grass-based and confinement dairy systems had similar carbon footprints per tonne of ECM. Emission algorithms and allocation of GHG emissions between milk and meat also affected the relative difference and order of dairy system carbon footprints. For instance, depending on the method chosen to allocate emissions between milk and meat, the relative difference between the carbon footprints of grass-based and confinement dairy systems varied by 3 to 22%. This indicates that further harmonization of several aspects of the LCA methodology is required to compare carbon footprints of contrasting dairy systems. In comparison to recent reports that assess the carbon footprint of milk from average Irish, UK, and US dairy systems, this case study indicates that top-performing herds of the respective nations have carbon footprints 27 to 32% lower than average dairy systems. Although differences between studies are partly explained by methodological inconsistency, the comparison suggests that potential exists to reduce the carbon footprint of milk in each of the nations by implementing practices that improve productivity.     

Potential influence of herd and animal factors on the yield of cheese and recovery of components from Sarda sheep milk,as determined by a laboratory bench-top model cheese-making

Individual milk samples from 169 Sarda sheep were collected to characterise the cheese-making potential through the use of a laboratory bench-top model cheese-manufacturing procedure. As the milk samples were not standardised before processing, the data collected at laboratory level fully reflected the great variability of milk from individual animals. The average cheese yield traits of fresh cheese, cheese dry matter and water retained in cheese (as percentages of the milk processed) were 20.6%, 10.1% and 10.6%. The average milk fat and protein recoveries in the curd were 94.0% and 76.7%, respectively. The values for daily production of curd and curd dry matter per sheep were 0.41 kg d⁻¹ and 0.20 kg d⁻¹, respectively. The cheese yield and cheese-related traits were mainly affected by the nutrient content of the milk and the individual effects of the stage of lactation and daily milk yield, respectively, but also by a large individual variation.     

Computer simulation of energy use,greenhouse gas emissions,and costs for alternative methods of processing fluid milk

Computer simulation is a useful tool for benchmarking electrical and fuel energy consumption and water use in a fluid milk plant. In this study, a computer simulation model of the fluid milk process based on high temperature, short time (HTST) pasteurization was extended to include models for processes for shelf-stable milk and extended shelf-life milk that may help prevent the loss or waste of milk that leads to increases in the greenhouse gas (GHG) emissions for fluid milk. The models were for UHT processing, crossflow microfiltration (MF) without HTST pasteurization, crossflow MF followed by HTST pasteurization (MF/HTST), crossflow MF/HTST with partial homogenization, and pulsed electric field (PEF) processing, and were incorporated into the existing model for the fluid milk process. Simulation trials were conducted assuming a production rate for the plants of 113.6 million liters of milk per year to produce only whole milk (3.25%) and 40% cream. Results showed that GHG emissions in the form of process-related CO₂ emissions, defined as CO₂ equivalents (e)/kg of raw milk processed (RMP), and specific energy consumptions (SEC) for electricity and natural gas use for the HTST process alone were 37.6 g of CO₂e/kg of RMP, 0.14 MJ/kg of RMP, and 0.13 MJ/kg of RMP, respectively. Emissions of CO₂ and SEC for electricity and natural gas use were highest for the PEF process, with values of 99.1 g of CO₂e/kg of RMP, 0.44 MJ/kg of RMP, and 0.10 MJ/kg of RMP, respectively, and lowest for the UHT process at 31.4 g of CO₂e/kg of RMP, 0.10 MJ/kg of RMP, and 0.17 MJ/kg of RMP. Estimated unit production costs associated with the various processes were lowest for the HTST process and MF/HTST with partial homogenization at $0.507/L and highest for the UHT process at $0.60/L. The increase in shelf life associated with the UHT and MF processes may eliminate some of the supply chain product and consumer losses and waste of milk and compensate for the small increases in GHG emissions or total SEC noted for these processes compared with HTST pasteurization alone. The water use calculated for the HTST and PEF processes were both 0.245 kg of water/kg of RMP. The highest water use was associated with the MF/HTST process, which required 0.333 kg of water/kg of RMP, with the additional water required for membrane cleaning. The simulation model is a benchmarking framework for current plant operations and a tool for evaluating the costs of process upgrades and new technologies that improve energy efficiency and water savings.     

Effect of the use of carbon dioxide on Prato cheese making

The effects of the addition of carbon dioxide (CO₂) under pressure (1.6 × 10⁵ Pa at 8 °C) to pasteurised Prato cheese milk (pH 6.0) was investigated through 120 d of refrigerated storage. The addition of CO₂ decreased the curd formation time (30 min), the total manufacturing time (47 min), and the pH of Prato cheese, thus leading to reduced moisture content. The CO₂ treated cheese showed higher firmness and fracturability due to the greater whey loss. In contrast, the microorganism counts, cheese yield, protein loss, cohesiveness, springiness, and gumminess were not significantly affected by the treatment. For the lactose fermentation, no significant differences were observed. The addition of CO₂ did not change the proteolysis indexes, and no significant differences were observed in the sensory acceptance of the CO₂ treated cheese, which was well accepted by consumers.     

Effects of intraruminal infusions of propionate and butyrate with two different protein supplements on milk production and blood metabolites in dairy cows receiving grass silage-based diet

Four cows were used in a balanced 4×4 Latin square with 2 week experimental periods to investigate the effects of intraruminal infusions of volatile fatty acids and protein source on milk production and blood metabolites. The four treatments in a 2×2 factorial arrangement were isoenergetic intraruminal infusions of propionate (500 g day⁻¹) or butyrate (417 g day⁻¹) each given with isonitrogenous protein supplementation of fish meal (FM) or barley protein (BP). The cows were fed restrictively with 9 kg dry matter day⁻¹ of formic acid treated grass silage and 8 kg day⁻¹ of concentrate. Propionate infusion increased milk yield (24·9 vs 23·4 kg day⁻¹; P<0·05), milk protein yield (832 vs 778 g day⁻¹; P=0·05) and milk lactose content (44·7 vs 43·5 g kg⁻¹; P<0·05) and yield (1113 vs 1023 g day⁻¹; P<0·01), whereas butyrate infusion was associated with a higher milk fat content (44·7 vs 39·4 g kg⁻¹; P<0·01) and yield (1033 vs 974 g day⁻¹; P<0·01). FM tended (P<0·10) to increase milk yield, but had no significant effects on milk composition or milk component yields compared with BP. Butyrate infusion increased blood ketones, plasma non-esterified fatty acids and glycine relative to propionate infusion. The concentrations of ammonia N in rumen fluid and urea in plasma and milk were similar for both protein supplements. The profile of amino acids in plasma was similar for both protein supplements except for the higher concentrations of phenylalanine, proline and tyrosine with BP. The results show that protein utilisation can be improved by increasing the supply of propionate from rumen fermentation in cows given a grass silage-based diet. © 1998 SCI.     

Survey of aflatoxins in maize tortillas from Mexico City

In Mexico, maize tortillas are consumed on a daily basis, leading to possible aflatoxin exposure. In a survey of 396 2-kg samples, taken over four sampling days in 2006 and 2007 from tortilla shops and supermarkets in Mexico City, aflatoxin levels were quantified by HPLC. In Mexico, the regulatory limit is 12?µg?kg^?1 total aflatoxins for maize tortillas. In this survey, 17% of tortillas contained aflatoxins at levels of 3–385?µg?kg^?1 or values below the limit of quantification (<LOQ) and, of these, 13% were >12?µg?kg^?1 and 87% were below the regulatory limit. Average aflatoxin concentrations in 56 contaminated samples were: AFB₁ (12.1?µg?kg^?1); AFB₂ (2.7?µg?kg^?1); AFG₁ (64.1?µg?kg^?1) and AFG₂ (3.7?µg?kg^?1), and total AF (20.3?µg?kg^?1).     

Effect of supercritical CO2 extraction process parameters on oil yield and pigment content from by‐product hemp cake

This research gives an insight into the possibility of exploiting the one of the food industry's by‐products – pressed hemp cake. The complete recovery of oil from pressed hemp cake was achieved. Residual oil that remained in cake after pressing was extracted with supercritical CO₂ by applying different process parameters. Optimal extraction conditions were determined using response surface methodology. Total pigment contents of the oils obtained were determined. Extraction pressure had the most significant influence on yield and pigment content of extracted hemp cake oil. Depending on the pressure, the chlorophyll a content ranged from 101.11 to 378.28 mg kg^?1 and chlorophyll b from 65.14 to 189.78 mg kg^?1, while total carotene content was in the range from 33.58 to 132.67 mg kg^?1. The remaining oil in pressed hemp cake after supercritical CO₂ extraction was determined to be 0.56 ± 0.08% and the defatted cake was rich in proteins and fibre.     

Somatic cell counts,chemical composition and coagulation properties of goat and sheep bulk tank milk

This study focused on the need for bulk milk tank somatic cell count (BMTSCC) thresholds and cut-off levels indicating a decrease in milk quality that consequently influences product quantity and quality. First, 226 ewes and 231 goat bulk tank milk samples were collected from different Israeli herds and coagulation properties were determined. Second, soft cheese was produced. No correlation of coagulation properties was found with BMTSCC for sheep milk up to 3264 × 10³ and goat milk up to 6452 × 10³ cells mL⁻¹. Coagulation properties of goat milk with cell count higher than the latter resulted in a significant decrease in curd firmness. For breeds and management system in Israel, 2500 × 10³ cells mL⁻¹ is suggested as the cut-off level for sheep and 3500 × 10³ cell mL⁻¹ for goats. The cell count cut-off level and milk price according to BMTSCC should be tested and then determined for every breed and management and final dairy product.     

Effects of goat cheese on Helicobacter pylori activity and gastrointestinal complaints

To investigate whether and how consumption of goats' milk cheese affects Helicobacter pylori activity in the stomach of infected subjects, a randomized, controlled and blind study was performed. Sixty volunteers consumed 4 × 25 g day⁻¹ “Gouda-type” cheese for 3 weeks, prepared from either goats' or cows' milk. The goats' milk cheese was rich in short- and medium-chain fatty acids. Immediately before the start and thereafter every seven days, H. pylori activity was measured by the ¹³C-urea breath test, and gastrointestinal well-being was recorded weekly by validated questionnaires. Neither goats' nor cows' milk cheese had any significant effect on H. pylori activity. Ingestion of both cheeses improved gastrointestinal well-being but had no effect on stool parameters. The difference of the total symptoms score was significant between day 0 and 21 in each dietary groups, but not between the goats' and cows' milk cheese.     

Antimicrobial agent detection in ewes’ milk by the microbial inhibitor test brilliant black reduction test—BRT AiM®

The detection limits of 24 antimicrobial agents were determined in ewes’ milk by one commercially available version of brilliant black reduction test, BRT Inhibitor Test with prediffusion AiM^® (BRT AiM^®). For each drug, eight concentrations were tested on 20 milk samples from individual ewes. The detection limits of the BRT AIM^® method were determined by means of logistic regression models: 6 μg kg⁻¹ amoxycillin, 6 μg kg⁻¹ ampicillin, 51 μg kg⁻¹ cloxacillin, 2 μg kg⁻¹ penicillin “G”, 230 μg kg⁻¹ cefadroxil, 1330 μg kg⁻¹ cephalosporin “C”; 270 μg kg⁻¹ cephalexin, 92 μg kg⁻¹ cefoperazone, 120 μg kg⁻¹ ceftiofur, 69 μg kg⁻¹ cefuroxime, 6000 μg kg⁻¹ streptomycin, 1200 μg kg⁻¹ gentamycin, 3700 μg kg⁻¹ neomycin, 630 μg kg⁻¹ erythromycin, 120 μg kg⁻¹ tylosin, 390 μg kg⁻¹ doxycycline, 5500 μg kg⁻¹ oxytetracycline, 6200 μg kg⁻¹ tetracycline, 5400 μg kg⁻¹ sulfadiazine, 3200 μg kg⁻¹ sulfamethoxazole, 6500 μg kg⁻¹ sulfamethoxypyridazine, 6200 μg kg⁻¹ sulfaquinoxaline, 22000 μg kg⁻¹ chloramphenicol and 4100 μg kg⁻¹ trimethoprim. The BRT AiM^® method presents detection limits for β-lactam antibiotics that are similar to those obtained as Maximum Residue Limits (MRLs) according to Regulation 2377/90 EEC as set out by the European Union. However, for other antimicrobial agents the estimated limits were higher than those of the EU-MRLs. It is therefore advisable to enhance the sensitivity of the method for the detection of the different antimicrobial groups or to develop a combined system of different microbiological inhibitor tests that would enable the detection of a greater number of antimicrobial agents.